I think tends to happen when you access the vehicle inventory while in the vehicle before existing. Seems to make all your personal inventory items inaccessible

Quick note -- This only affects the host of the listen server. Clients that join will see the host and other clients properly interpolated. The host of the listen server will not see any interpolation on players whatsoever. If a client enters a vehicle, the vehicle's movement will be interpolated, but the player's animations still will not be.

I tested this also, cannot reproduce. Here's what I did:

Also tested in gamemaster mode as well, same thing happens.

I have done further testing, I think it may be more reproducable.
I notice this most often happens when entering a vehicle, and then interacting with the vehicle cargo.
Suggested steps.
Enter vehicle, and drive
Open inventory, and swap some items around to/from the cargo area.
Exit the vehicle and test you can reload weapons, swap weapons or pick up /drop items.

Hello AaronStatic.
It is very likely this will be in the later major update yes.

I am still getting this error. Replicated reliably by loading the following mods:

fixed with 0.9.9.97 (14Sept23 patch)

Hi. Nothing really changed on my end really. I just open up stable build then record the fps. After that exit game, and run the experimental build, and record the fps. Nothing major changed except running different build.
Interestingly, on current stable build 0.9.9.97 I have good fps just like the previous stable build. Only on experimental build I got performance hit. Strange indeed...